Miniature rotary stepping switch



July 23, 1968 H. G. GRUNDIG ET AL 3,394,

MINIATURE ROTARY STEPPING SWITCH Filed Oct. 12, 1966 5 Sheets-Sheet 1 Fig. la

26 g /5 10 ,1 4 3/ 5 /2 v i 8 6 4' i INVENTOR H. G. GRUU DIG W. ROSL BYFQ MJ ATTORNEY July 23, 1968 H. G. GRUNDIG ET AL 7 3,394,236

MINIATURE ROTARY STEPPING SWITCH Filed Oct. 12, 1966 5 Sheets-Sheet 2 W Fig. 20

l6 l7 K5 INVENTOR H. G. GRUNDIG W. ROSL ATTORNEY July 23, 1968 H. s. GRUNDIG ET AL 3,394,

I MINIATURE ROTARY STEPPING SWITCH Filed Oct. 12, 196$ 5 Sheets-Sheet 5 mvmon H.G.GRUND IG W. ROSL BY TTORNEY July 23, 1968 GRUNDlG ET AL 3,394,236

I MINIATURE ROTARY STEPPING SWITCH Filed Oct. 12, 196?: 5 Sheets-Sheet 4 Fig. 4 a

INVENTOR H.G.GRUNDIG W. ROSL July 23, 1968 H. G. GRUNDIG ET AL 3,394,

MINIATURE ROTARY STEPPING SWITCH Filed Oct. 12, 1966 5 Sheets-Sheet 5 4 UUU 060 ,39

INVENTOR H.G.GRUN DIG W. ROSL Uu-wamzu) ATTORNEY U i ed S t s Pat fo" 3,394,236 MINIATURE ROTARY STEPPING SWITCH Heinz Georg Grundig, Eckenhaid, and Wolfgang Ros], Heilsbronn, Middle Franconia, Germany, assignors to International Standard Electric Corporation, New York,

N.Y., a corporation of Delaware Filed Oct. 12, 1966, Ser. No. 586,196 Claims priority, application Germany, Oct. 12, 1965,

S 54,528 1 7 Claims. (Cl. 200-11) ABSTRACT OF THE DISCLOSURE A miniature rotary switch comprising a stator carrying a plurality of stationary contacts and a rotor mounted for rotational movement with respect to the stator. Movable contacts are resiliently mounted in recesses in the rotor so as to be biased in the direction of the fixed contacts. The rotor and switch housing embody holding means which resiliently hold the rotor with respect to the housing.

v The present innovation relates to a miniature rotary switch comprising a stator consisting of a cylindrical plate of insulating material provided with recesses for receiving the stationary contact members, further a rotor capable of being rotated on the stator, and in which the movable contact members are supported in a resilient fashion, and a pot-shaped housing, the circumference of which is provided with several engaging positions co-operating with a holding member arranged on the rotor.

Switches of these types are required in the communications and telecommunications art, as well as in the fields of measuring and control engineering.

Rotary switches of the aforementioned kind are described in the German Utility Model (Gebrauchsmuster) 1,885,960. In this petty patent there are described good types of embodiments of switches capable of being successfully used for many switching applications. In order to enable a universal use of these switches, however, constructional modifications have to be carried out, as may be taken from the following considerations.

In conventional types of switches the plastics part of the rotor carrying the movable contact members, is detachably connected to the driving shaft with the aid of a metallic holding arrangement. To this end the holding arrangement is provided with resilient projections or offset portions aimed at engaging grooves provided in the plastics part. In addition thereto, the holding arrangemerit is at the same time designed as a hold member for the engaging positions provided at the housing. To this end the holding arrangement comprises a tunnel which is arranged vertically in relation to the driving shaft, in which two balls are arranged which are being pressed towards the outside by the action of a spring arranged therebetween. At these points, impressions are provided .on the inside wall of the housing, for acting as engaging teeth. This construction'has the disadvantage that there is required a plastics part which has to be exactly fitted into the metallic holding arrangement, and that the holding arrangement itself must be of a relatively precise design. Moreover, the holding arrangement does not have the stability which it would have to have for performing its function as a holding member of the engaging support.

Likewise, also the plastics part, as used in the convental case for carrying the movable contact members, has certain disadvantages. This plastics part, consisting e.g. f polytetrafluoroethylene, is composed of two injectionmoulded parts which are welded to one another. As is well known, such a welding is ditlicult to be carried out.

3,394,236 Patented July 23, 1968 ice In addition thereto, the contact members which are resiliently supported in cavities or recesses provided on one side of the plastics part, are not joined to the plastics part in a captive manner, so that on account of this the assembly becomes unpractical.

A further disadvantage of the conventional types of switches resides in the fact that the rotor composed of the contact and the hold member, is incapable of being centered. For this reason, it may happen that the rotor is eccentrically connected to the driving shaft, which should be avoided at all events.

Moreover, certain disadvantages become evident from the way of mounting the stationary contact members, because the twisting of the ends designed as soldering lugs, at the specially provided indents, is likely to cause cracks and breaks.

Finally, also the conventional type of switch housing is featured by certain disadvantages, i.e. by the type of embodiment of the threaded bushing serving both as a bearing and the mounting. Up to now this bushing has been designed in such a way that the stop collar serving the rotor is changed when being riveted to the housing, as regards its position in relation to the upper edge of the housing, which can easily have a detrimental eflect upon the contact-making between the movable and the stationary contacts.

It is one object of the present innovation to overcome the aforementioned disadvantages in a simple, effective, and economical way, but in particular to enlarge the range of practical application of the conventional types of switches which was hitherto rather restricted.

With respect to the switch of the type described hereinbefore, this problem is solved in accordance with the present innovation in that the rotor consists of two cylindrical discs which are firmly joined to one another and which are lying behind each other in the axial direction, of which the disc adjacent to the bottom of the housing, is designed as a hold member of the engaging support, whereas the other disc comprises correspondingly shaped recesses for receiving the resiliently supported contact members, and that between the two discs there is arranged a thin plate against which rest the springs of the movable contact members.

The innovation will now be explained in detail with reference to the copending drawings. FIGS. 1a to 10 show sectional elevations taken through the switch according to the innovation. In FIG. la there is shown a longitudinal section taken through the switch, whereas FIGS. 1b and 10 show sectional views along the dot-and-dash line in FIG. 1a, in accordance with the arrows shown therein. In FIGS. 2a and 2b there is shown the rotor as connected to the driving shaft, both in a sectional elevation and in a top view. FIGS. 3a to 30 show the plate of insulating material with the stationary contact members, both in a sectional and a top view. In FIGS. 4a and 4b there is shown the housing with the bearing or supporting and the mounting bushing, both in a sectional and a top view. Finally, in FIG. 5 there is shown the basic principle of a switch comprising a double shaft drive according to the innovation, in a front view.

The switch according to the innovation substantially consists of three structural groups, as may be taken from FIGS. la to la. One of these structural groups is constituted by the stator 1 which, in the manner known per se, consists of a cylindrical plate of insulating material, e.g. of ceramics, carrying the stationary contact members 2 and 3. The second of these structural groups includes the rotor consisting of the contact element 4 and the hold element 5, together with the contact members 6 and the driving shaft 7. The third of these groups consists of the pot-shaped metal housing 8 with the threaded bushing 9 riveted therein, serving as the bearing for the driving 3 shaft, and for mounting the switch. The individual structural groups will now be described in greater detail hereinafter.

As is also evident from FIG. 2a, the rotor consists of two cylindrical discs 4 and 5 which are arranged behind each other in the axial direction, of which the disc 5, which is arranged adjacent the bottom of the housing, is designed as the hold member of an engaging support. This hold member, consisting of metal and manufactured as 2. turned part, has a somewhat smaller diameter than the contact elements before carrying the movable contact members 6, and comprises two tunnels and 11 arranged diametrically opposite each other, and intersecting the driving shaft 7 in the vertical direction. Each of these tunnels incorporates a ball 12 or 13 which is pressed against an engaging position provided in the inside wall of the'housing by the action of a spring 14 or 15 lying therebehind respectively. These engaging positions consist in the manner known per se of indentations or impressions provided in the housing 8. The metallic hold member 5 is joined in a captive manner to the driving shaft 7, e.g. by way of riveting. To this end a throughgoing drill-hole 16 is provided in the hold member. On its side facing the housing 8, the hold member carries a projecting pin 17 or the like, co-operating with a limiting stop system of the type known per se, for restricting the range of rotary motion.

The disc 4 of the rotor, which is designed as a contact element, and is made of a plastics material, such as polytetrafluorethylene, by way of injection-moulding, comprises correspondingly shaped recesses or openings 13 for receiving spring-mounted U-shaped contact members 6. In the inside of the slotlike openings there are provided cross-sectional constrictions 19 meeting against the U- shaped bridges with extensions 20 projecting towards the outside. By the action of the springs 21 which, by a cylindrical enlargement 22, are received in the centre of the slotlike openings, the contact bridges are pressed towards the outside against the contact members 2 and 3 of the stator 1. The springs 21 rest at the other end, on a small plate 23 of insulating material which is arranged between the hold member 5 and the contact element 4, consisting e.g. of polytetrafiuorethylene-glass fabric.

The three parts of the rotor, namely the contact element 4, the hold element 5 and the small plate of insulating material 23 lying therebetween, are firmly mounted to one another with the aid of at least two rivets 24 which are inserted in the axial direction through fitting drillholes, in that the headless ends, as positioned in the hold element, are deformed. The finished rotor, which is still firmly connected to the driving shaft via the hold element, is provided with a central opening 25 tightly fitting on the drive shaft, so that the rotor is centered. This arrangement is inserted in the housing 8, and is fixed in the axial direction with theaid of a safety device 26 of the type known per se.

The stationary contact members, e.g. the contact laminations 2 and the contact rings 3 of the stator co-operate with the U-shaped contact bridges of the rotor. For receiving these contact members, the arrangement and mounting of which is shown in FIGS. 3a to 30, there is provided in the manner known per se a ceramic plate with smooth openings. The inner contact members 3 are arranged concentrically, i.e. in the form of an uninterrupted circle, whereas the outer contact members 2 are mounted at an angle in relation to this circle and may, in addition thereto, be angled off at the ends 27. The mounting of the stationary contact members is effected by way of heading or upsetting a shoulder 28 of the ends 27 designed as soldering lugs, on the side not facing the moving contact members. As a contact material there are provided rare or noble metals, such as silver, palladium, etc.

In order that the driving shaft, if so required, may be led through the stator, the latter is provided with a cen- .4. tral opening 29 easily fitting onto the driving shaft. Alon the circumference of the stator there are provided in the manner known per se, recesses or openings 30 which are engaged towards the centre, by bent, flap-shaped projections of the housing 8, thus protecting the stator against being twisted.

The housing of the switch, according to the showing of FIGS. 4a and 4b, consists in the manner known per se, of a cylindrical pot 8 of a drawn sheet metal into which, at the height of the engaging balls 12 and 13, engaging teeth 31 are pressed into the circumference. The number of these impressions is in accordance with the number of switching positions that are provided. This engaging element, together with the hold element 5 of the rotor, constitutes the engaging support of the switch.

Into the housing there is inserted a non-mounted limit stop ring 32 which, together with the limit stop pin 17 of the hold element 5, constitutes the limit stop system of the type known per se. The limit stop ring is provided along its circumference with extensions 33 corresponding to the engaging teeth 31, so that it will rest in a nonrotatable manner on the bottom of the housing. In addition thereto, the limit stop ring, at its inner circumference, is provided with a number of limit stop teeth 44. For restricting the range of rotation, in accordance with the desired number of steps, one or more of the limit stop teeth are removed. Accordingly, when using the same switch housing, it is possible to manufacture the most various types of switches as regards the range of rotation and the number of steps.

At the closed end of the housing 8, and in a manner known per se, the threaded bushing 9 is mounted in a torsion proof manner by way of a rolling riveting. This bushing serves as the bearing for the driving shaft 7 and for mounting the switch. At its end facing the inside of the housing, the bushing is provided with the stop collar 34 projecting over the rivet collar 35. In this way it is safeguarded that the rotor resting against the collar 34 with respect to its position in relation to the top edge 36 of the housing part and, consequently, to the stator plate 1 resting on this edge of the housing, is not being changed by the riveting, so that both the rotor and the stator cooperate in a manner safeguarding a reliable switching operation.

The stator plate is secured against twisting, in the manner known per se, by way of providing flap-shaped projections or extensions 37 engaging the openings or recesses 30' provided in the stator plate. For fixing the stator plate, the tapered ends 38 of these extensions or projections, sub sequently to the insertion of the stator plate, are bent towards the centre.

In FIG. 5 there is shown a further modified type of embodiment of a miniature rotary stepping switch according to'the present innovation. It has proved to be of advantage to design the driving shaft 7 of the switch 39 as a hollow shaft, so that the driving shaft 40 of a second miniature type rotary stepping switch 41 may be inserted therethrough. If this driving shaft projects over the driving shaft of the first switch, it is possible that both switches may be operated independently of one another. The two miniature rotary switches are fixed in the axial direction by means of distance or separator pieces 42 connecting the assembly sheets 43 on which the switches are mounted, to one another.

In order to enable also the performance of more complicated switching processes, it is possible to combine more than two switches in one constructional group. Thus, for example, the driving shaft of a third switch may be connected to the projecting driving shaft of the second switch via a coupling member, so that both switches are capable of being operated in common. In this case it is of advantage to design the rotor of the third switch without a hold member, so that the pot-shaped housing may be designed correspondingly low. It is also possible, however, to use instead of the second or the third switch a 9 present innovation, due to its simple construction and the simple types of individual parts employed thereby, may be manufactured to have small dimensions. In one example of embodiment the external diameter of the switch only amounts to 16 mm. In this case the rotor carries up to six spring-mounted contact bridges. The engaging support in this type of embodiment is designed to consist of twelve parts. The contacts may be designed and arranged for a bridging as well as for an interrupting switching mode. Since for the individual parts of the switch there are only used relatively temperature-resistant materials, the switch according to the innovation is also suitable for being operated under relatively high operating temperatures.

We claim:

1. A miniature rotary switch comprising: a rotor and a stator concentrically positioned in a housing; said stator carrying a plurality of circularly arranged stationary contacts exposed at the face thereof adjacent to said rotor; said rotor including a pair of coaxial discs and a thin plate interposed therebetween; means fixedly connecting said discs and plate together for common rotation with respect to said stator; said housing and the disc remote from said stator embodying holding means for resiliently holding said rotor with respect to said housing; the other disc adjacent to said stator being formed with a plurality of circularly arranged recesses; a movable contact positioned in each recess; spring means interposed between the movable contact in each of said recesses and said plate biasing each movable contact toward the stationary contacts; and shoulder means in each recess cooperating with the contact therein for limiting movement of the contact toward said stationary contacts.

2. A miniature rotary switch as set forth in claim 1 wherein the disc remote from said stator is formed of metal; said other disc is formed of plastic; and said plate is formed of an insulating material.

3. A miniature rotary switch as set forth in claim 1 including a drive shaft for said rotor; and means fixedly securing said disc which is remote from said stator directly to said drive shaft.

4. A miniature rotary switch as set forth in claim 1 wherein each movable contact is a U-shaped element, the legs of said U-shaped element extending axially and embodying lateral projections which bear against said shoulder means by the force of said spring means.

5. A miniature rotary switch as set forth in claim 1 wherein said stationary contacts extend through said stator beyond the other face thereof, and the portion of said stationary contacts adjacent to said other face are deformed to retain said contacts in said stator.

6. A miniature rotary switch as set forth in claim 1 wherein said stator closes one end of said housing, said housing embodying flap-shaped extensions engaging corresponding axially extending recesses along the periphery of said stator and bent inwardly against the other face of said stator to fixedly retain the latter in said housing.

7. A miniature rotary switch as set forth in claim 3 including a bushing at the end of said housing opposite to said stator, said shaft being rotatably supported in said bushing a portion of said bushing behind the inner end thereof being deformed to provide a rivet collar securing said bushing to said housing, limit stop means for said rotor including a stop ring surrounding said rivet collar, and said rotor being directly engagea-ble with said inner end of said bushing.

References Cited UNITED STATES PATENTS 1,664,110 3/1928 Jacobi 20044 1,744,245 1/ 1930 Sandin 200-44 XR 2,499,622 3/1950 Baker et al. 200 3,297,836 1/1937 OMalley 2001l ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

